I live in the Southwest and occasionally we get epic dust storms. They blind, confuse and generally make life miserable, which is why they are perfect RPG encounters. Not to mention the fact, for me at least, I can describe them in intimate detail from first hand experience. To share a bit of that experience, I invite you to check out some home video I shot about an hour ago of my street. The storm actually got worse about ten minutes after I shot the video! Truly blinding. For those not familiar with a real dust storm, this should provide all the inspiration you need to torture your party of PCs!